Dialkylmagnesium compounds are well known in the art. However, the production of soluble dialkylmagnesium compounds, free of solvation and chloride, by the direct reaction of magnesium with a halide, has heretofore been unsuccessful except in very specific systems. Thus, Glaze and Selman, Journal of Organometallic Chemistry, volume 5, page 477 (1967), produced soluble di-n-amylmagnesium by reaction of powdered magnesium metal with n-amyl chloride and then refluxing the product with benzene. W. N. Smith, Jr. (J. Organometal Chem., 64, 25 (1974) investigated the direct reaction of alkyl halides, especially long chain n-alkyl halides, with magnesium in the absence of organic bases. The resultant products, however, often showed limited solubility and/or high residual halogen content. These methods, however, are imapplicable to other dialkylmagnesium compounds, particularly n-butyl or lower primary alkyl-magnesium compounds, due to their high degree of insolubility. In fact, Kamienski and Eastham, in the Journal of Organic Chemistry, volume 34, page 1116 (1968), found it impossible to prepare di-sec-butylmagnesium by the Glaze and Selman method. They were able to prepare di-sec-butyl chloride in the presence of an ether catalys, but the resultant product contained soluble chloride. These same authors were able to prepare hydrocarbon solutions of di-sec-butylmagnesium by an exchange process employing an activated form of magnesium chloride and sec-butyllithium in hydrocarbon media. However, this synthetic technique is not applicable to most magnesium alkyls, since these compounds are generally insoluble in hydrocarbon.
Various organoaluminum-organomagnesium complexes have been prepared by the reaction of a trialkylaluminum compound with a desolvated (ether-free) Grignard reagent, by electrolysis of mixtures of alkali metal tetraalkylaluminates using a magnesium anode, and by the reaction of dialkylmagnesium compounds, prepared via the mercury-magnesium exchange method, with trialkyl-aluminum compounds. The complexes prepared by these processes have low Mg/Al ratios, in the range of 0.5 to 1.0 depending upon the stoichiometry of starting materials.
The electrolysis method requires the use of mixed R.sub.4 AlM compounds (M=alkali metal) in a molten state and the preferred temperature range is 100.degree.-125.degree. C. See for example, U.S. Pat. No. 3,028,319. This temperature range precludes the preparation of complexes which may be easily pyrolyzed, for example, when R=isobutyl. Furthermore, complexes with Mg/Al ratios greater than 0.5 are not produced by this procedure.
The complexes Me.sub.8 Al.sub.2 Mg and Me.sub.5 AlMg prepared by the procedure of Stucky and Atwood, Journal of the American Chemical Society, volume 91, page 2538 (1969), had significantly different properties than supposedly the same compounds prepared earlier by Ziegler, Annalen der Chemie, volume 605, page 93 (1957). The discrepancy may be due to incomplete removal of ether in the Grignard reagent used by Ziegler, since dialkylmagnesium and Grignard reagents reagents are known to be difficult to free of complexed ethers.
Recently, hydrocarbon soluble magnesium alkylaluminum alkyl complexes were prepared by interaction of organo-aluminum compounds with the reaction product of magnesium with alkyl halides (U.S. Pat. No. 3,737,393).
It is an object of the present invention to prepare hydrocarbon soluble organomagnesium complexes, including those complexes containing the normally insoluble lower dialkylmagnesium compounds suitable for use as co-catalysts for the polymerization of olefins, diolefins, or olefin oxides.
It is another object of the present invention to prepare organomagnesium complexes wherein the Mg/M ratio is about 1 or greater. Other objects of the present invention will become apparent from the description contained below.